Insights into the Response of Soybean Mitochondrial Proteins to Various Sizes of Aluminum Oxide Nanoparticles under Flooding Stress

Rapid developments in nanotechnology have led to the increasing use of nanoparticles (NPs) in the agricultural sector. For possible interactions between NPs and crops under flooding stress to be investigated, the molecular mechanisms in soybeans affected by exposure to various sizes of Al₂O₃ NPs were analyzed using a proteomic technique. In plants exposed to 30–60 nm Al₂O₃ NPs, the length of the root including hypocotyl was increased, and proteins related to glycolysis were suppressed. Exposure to 30–60 nm Al₂O₃ NPs mediated the scavenging activity of cells by regulating the ascorbate/glutathione pathway. Hierarchical clustering analysis indicated that ribosomal proteins were also increased upon exposure to flooding-stressed plants with 30–60 nm Al₂O₃ NPs. Mitochondrion was the target organelle of Al₂O₃ NPs under flooding-stress conditions. Mitochondrial proteomic analysis revealed that the abundance of voltage-dependent anion channel protein was increased upon exposure to flooding-stressed soybeans with 135 nm Al₂O₃ NPs, indicating the permeability of the mitochondrial membrane was increased. Furthermore, isocitrate dehydrogenase was increased upon exposure of plants to 5 nm Al₂O₃ NPs under flooding conditions. These results suggest that Al₂O₃ NPs of various sizes affect mitochondrial proteins under flooding stress by regulating membrane permeability and tricarboxylic acid cycle activity.